I know Iran and West were fairly close before the revolution, and probably US's closest ally in the region besides Israel. As far as I understand they even had exclusive access to some US military equipment that even other allies didn't have access to (F14).
So my question is this, Was there every any interest/attempt from either side to have Iran join NATO?
In fact Iran was part of an organization modelled on NATO, called the Central Treaty Organization (CENTO) [1]. Established in 1955, the organization initially included the UK, Turkey, Iraq, Iran and Pakistan. Despite being key to its formation, The US never became a full member, due to internal US politics.
Ultimately, this attempt to extend the NATO model to countries on the southern flank of the USSR failed. In reality it was not a natural alliance of like-minded nations but more a mish-mash of countries aligned to various extents with the US that the US tried to strong-arm and bribe into forming a coherent bloc.
Iraq pulled out in 1958. When Pakistan when to war with India in 1974 it tried to enlist the help of the alliance (to little effect). The nail in the coffin was the Iranian revolution of 1979, after which the organization was dissolved.
[1] https://en.wikipedia.org/wiki/Central_Treaty_Organization